Define Stirring Objectives

• Determine the purpose, such as liquid–liquid mixing, solid–liquid suspension, gas–liquid or liquid–liquid dispersion.
• Consider whether the process requires heat transfer, absorption, extraction, dissolution, crystallization, etc.
• Select the impeller type according to process requirements.

Calculate Stirring Power Requirement

• Power required during mixing can be estimated using the formula: P=Np×ρ×N3×D5P = N_p \times \rho \times N^3 \times D^5P=Np​×ρ×N3×D5 where N_p = power number (depends on system design),
  ρ = liquid density,
  N = rotational speed,
  D = impeller diameter.
• The power number is complex to determine, influenced by tank diameter, impeller diameter, blade width, blade angle, number of blades, viscosity, and baffle design.

Motor Power Selection

• The selected motor power (after efficiency consideration) should be ≥ 1.5 × the calculated stirring power.

Minimum Stirring Speed

• Determine the minimum operating speed required to achieve the mixing objective, not merely the critical speed of the shaft.

Strength and Rigidity Check

• Verify the strength and stiffness of the stirrer shaft and impeller according to the calculated power.

Reducer Selection

• When using a gearbox, consider the service factor and load capacity of the reducer.

Shaft Support

• For long shafts, additional supports may be required at the middle or bottom.

Installation Method

• Decide on the installation approach in advance: top-entry, bottom-entry, or side-entry.

Support Structure Design

• Design the support base according to the installation method and operating conditions.

Sealing Method

• Select suitable sealing type, e.g., packing seal or mechanical seal.